One of the key concepts in Navarro's book is the idea of "baseline" behavior. Our baseline behavior refers to our normal, relaxed state of being, which serves as a reference point for analyzing our nonverbal cues. When we're in a state of stress, anxiety, or excitement, our body language deviates from our baseline, revealing subtle changes that can be detected by trained observers. By establishing a person's baseline behavior, we can identify potential inconsistencies or anomalies in their nonverbal communication, which may indicate dishonesty or hidden emotions.